Premix Burner Pilot Gas System for Combustion Stability
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Solution Overview
Problem
Existing premix burners for gas turbines have a narrow stability range, making them susceptible to changing operating conditions and fuel compositions, requiring complex control systems and sensitive fuel supply management.
Innovation Solution
A method and premix burner design that injects a gas-air mixture via a swirler with a central pilot gas system using at least two partial streams of diffusion fuel with different orientations, enhancing stability and flexibility by mimicking premixing effects, with axial and inclined diffusion nozzles positioned to minimize mixing and maximize stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a lean gas-air mixture is used in the main injection system, then harmful emissions are reduced, but the combustion process stability deteriorates
Solution Approach 1:
The fuel injection system is segmented into a main injection system (for lean mixture and emission control) and a separate pilot gas system (for stability). The pilot flame provides reliable ignition and stabilization while the main lean mixture controls emissions, dividing the conflicting functions into separate subsystems.
Solution Approach 2:
The pilot flame acts as an intermediary between the lean main gas-air mixture and the combustion process. It provides the necessary ignition energy and stabilization without requiring the main mixture to be rich, thus enabling both low emissions and stable combustion.
2Reliability
If the combustion process stability is prioritized using a pilot flame, then the stability range is improved, but harmful emissions increase
Solution Approach 1:
The pilot gas system operates locally with a small amount of fuel near the ignition orifice to provide stability, while the main injection system operates with a lean mixture throughout the combustion chamber to control emissions. Each zone has optimized fuel-air ratio for its specific function.
3Reliability
If a multi-stage pilot gas system is used to enlarge stability range, then combustion stability is improved, but device complexity increases
Solution Approach 1:
The stability-enabling function is extracted from the main injection system and placed in a dedicated pilot gas system. This separation simplifies the control logic compared to attempting to achieve stability through complex multi-stage control of the main system, as the pilot system only needs to maintain a small stabilizing flame.
4Productivity
If the premix burner is made sensitive to changing fuel compositions for precise control, then combustion efficiency is improved, but adaptability to fuel quality changes deteriorates
Solution Approach 1:
The pilot flame automatically adapts to changing fuel compositions in the main supply without requiring active control adjustments. The diffusion fuel in the pilot system self-regulates to maintain stable combustion regardless of variations in the premixed fuel quality, providing inherent adaptability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a more stable and adaptable combustion process under varying fuel conditions, improving flexibility and reducing sensitivity to changes in fuel compositions and qualities without complex control mechanisms.
Implementation Method 1
A gas-air mixture is injected by a main injector into a flame chamber via a swirler
Implementation Method 2
A diffusion fuel of a central pilot gas system is injected into the flame chamber in the form of at least two partial streams with different directions or orientations
Implementation Method 3
combustion processes which are spark-ignited but which are then self-running
Data Source
AI summary
A method for operating a premix burner for gaseous fuels having a multi-stage pilot gas system whose diffusion fuel is injected into a flame chamber of the premix burner as at least two partial streams with different orientations, and a premix burner for carrying out the method.